And as the protests entered their third month, authorities freed several dissidents on Sunday who had been held in connection with the unrest, after offering to launch a dialogue with the opposition.
"At least seven people, including two women, were killed by security forces who are indiscriminately shelling four districts in the town," of Tall Kalakh, a rights activist told AFP by phone, quoting witnesses.
Earlier a resident said three people were killed in the western town, where the army had deployed, and that there were many wounded people who could not be evacuated.
The resident, reached by telephone, told AFP that snipers stationed on rooftops had killed three men as they left a sit-in protest in a mosque.
Syrian troops were deployed in force in the town of some 25,000 inhabitants, he said as gunfire rattled in the background.
The bloodshed spilled into Lebanon on Sunday when a Syrian woman, among dozens fleeing Tall Kalakh, was killed and six other people wounded, a Lebanese security official said.
Gunfire from Syria raked a crowd at Al-Boqayah crossing, near north Lebanon's border town of Wadi Khaled, the official said. A Lebanese soldier was among those wounded.
Another Lebanese security official said two Syrian border guards were among those fleeing Tall Kalakh, and that one of them was wounded and later died of his injuries in Lebanon.
Hundreds of people have fled Tall Kalakh since Friday amid a brutal crackdown by authorities bidding to crush an unprecedented revolt against Assad's regime.
The pope said after his weekly Angelus prayer in Rome's St Peter's Square: "I ask God that there be no further bloodshed in (Syria), this country of great religions and civilisations.
"It is urgent to restore cohabitation," the pontiff said.
On another front, Israeli gunfire killed two pro-Palestinian protesters and wounded dozens as civilians crossed from Syria onto the annexed Golan Heights on Sunday, raising tensions between Damascus and the Jewish state.
The Israeli army accused Assad's regime of "organising" the violence as a means to divert international attention from the pro-democracy movement sweeping Syria.
The unrest came as Palestinians in the occupied territories, inside Israel and across the region marked the anniversary of the Jewish state's 1948 creation, known in Arabic as the "nakba" or "catastrophe."
Meanwhile Syrian authorities freed several dissidents, including prominent opposition figure and former MP Riad Seif and rights activist Catherine Talli, human rights groups said.
They were released two days after Information Minister Adnan Mahmud said a "national dialogue" would be launched with opposition figures as part of efforts by the government to forge ahead with reforms.
Up to 850 people have been killed and at least 8,000 arrested since the protests started in mid-March, rights groups say.
The regime has blamed the deadly violence on "armed terrorist gangs" backed by Islamists and foreign agitators.
At least four people were shot dead on Saturday by security forces in Tall Kalakh and several wounded as thousands held a second day of anti-regime protests, a witness and a medic said.
To prevent casualties from being arrested or "finished off," the wounded were treated in a small clinic rather than the state hospital, another witness in Tall Kalakh said.
Security forces on Saturday fired at a funeral convoy at an entrance to the town, killing the mother and wounding three family members of a victim of the clashes, according to the Tall Kalakh resident.
A pro-regime newspaper, Al-Watan, said armed men had fled the cities of Banias and Homs and sought refuge in Tall Kalakh, while "fighters" from Lebanon had entered Syria.
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